ESC 301 ECOLOGY-Part C Ferhan Çeçen

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Climate and Major Biomes
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Abiotic Effects of Latitude and Altitude
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Succession and Disturbance
• Ecological succession: transition between biotic communities
– Primary: no previous biotic community – Secondary: previously occupied by a community – Aquatic: transition from pond or lake to terrestrial community
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Material Cycles
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snow or fog supports all terrestrial ecosystems. – Water that condenses over land surfaces. but solar energy continually evaporates this water.
.Hydrological Cycle (Water Cycle)
– Most of earth’s water is stored in the oceans. and winds distribute water vapor around the globe. in the form of rain.

. • Eventually.Water Cycle
• Living organisms emit the moisture to the atmosphere through respiration and perspiration. this moisture re-enters the atmosphere or enters lakes and streams and ultimately the oceans.

WATER CYCLE
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.Carbon Cycle
• Carbon serves a dual purpose for organisms:
– Carbon is a structural component of organic molecules (C6H12O6. – The carbon cycle begins with photosynthetic organisms that take up (CO2. carbon dioxide) to form starch. – Starch is taken up by several organisms. digested in stomach and simple sugars get broken down to simpler ones (CO2 . sugar) – Chemical bonds provide metabolic energy. H20 & energy).

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• Sugar molecules either undergo respiration and release carbon in the form of C02.Carbon cycle (contd. • When organisms decay carbon returns to nature.
. • From simple sugar also large organic molecules can be formed.

. • Nitrogen is a primary component of many household products (Ammonia and others) and agriculture fertilizers. • Nitrogen is a very important nutrient for living things.Nitrogen cycle
• Several organic molecules contain nitrogen • Amino acids. peptides and proteins are large organic molecules that living organisms need for their existence.

– Plants acquire nitrogen through the nitrogen cycle.)
• Nitrogen makes up about 78% of the air. – Nitrogen-fixing bacteria (live in roots of legumes) and blue-green algae) are highly organised to fix nitrogen of the atmosphere to ammonia ( N2 to NH3) – They combine hydrogen of atmosphere with nitrogen and form ammonia (NH3)
. the stable diatomic molecule in air. but plants cannot use N2.Nitrogen Cycle (cont.

• After plants cells absorb nitrates. • There are aerobic bacteria oxidizing nitrite further to nitrate (NO3-). inorganic nitrogen is converted into an organic form. • This conversion of ammonia to nitrate is called nitrification.)
• Ammonia in plants is used to make amino acids which is used as building blocks to form protein (a polypeptide chain made up of several amino acids).which green plants can absorb and use.
.Nitrogen cycle (contd. these nitrates are reduced to ammonia (NH3) and then used by the plant.Thus. • There are aerobic bacteria oxidizing ammonia to nitrite (NO2-).

This is called denitrification. This process is known as ammonification. • Denitrifying bacteria reduce nitrates in soil or water to nitrogen gas (N2). converting organically bound nitrogen into ammonia.)
• Fungi and bacteria decay dead organisms.Nitrogen cycle (cont. which is also converted to ammonia by ammonification. which is released into the atmosphere.
. Animals produce urine which contains nitrogenous compounds such as urea.

Nitrogen cycle
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General Ecology
. Krohne.Nitrogen cycle
Modified from D. T.

Nitrogen Cycle
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Nitrogen Cycle
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Nitrogen cycle
Critical Thinking Issue – How are Human Activities Affecting the Nitrogen Cycle?
Effects of increased use of nitrogen fertilizers:
Eutrophication of water bodies Nitrates in drinking water
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